Strand tension control device



y 1961 cs. PERRELLA 2,983,468

STRAND TENSION CONTROL DEVICE Filed Dec. 22, 1959 I1 ENTOR Jail? jz/wllh/ ATTORNEY United States Patent STRAND TENSION CONTROL DEVICE Guido Perrella, Montreal, Quebec, Canada, assignor to Clix Fastener Corporation, Montreal, Quebec, Canada Filed Dec. 22, 1959, $61. No. 861,332 12 Claims. or. 242-1562 This invention relates to devices for controlling the tension of strands, such as yarns, threads, and the like, as they are being withdrawn from a supply spool.

It is frequently desirable, if not essential, to maintain uniform tension in the strands being withdrawn from a supply spool. For instance, in the supplying of selvage warp threads or yarns from a spool to the weaving mechanism of a loom, a. tension control device is usually provided to ensure uniform tension in the yarn supply to the loom. For obvious reasons, it is desirable that the yarns supplied to the loom should be under a constant, uniform tension. Thus, steps must be taken to counteract the many incidental factors which may cause varia- .tions in tension such as the varying diameter and'weight of the spool, the irregular speeds of withdrawal of yarns from the spool, and the intermittent nature of the periods of withdrawal of yarns from the spool.

20 has a relatively short forwardly extending arm 21 and a relatively long rearwardly extending arm 22.

A free running roller 23 is carried by the lever arm 22. Preferably the position of roller 23 in the arm 22 may be adjusted by means of a slot 24 and a cooperating clamp 25'. It will be apparent that swinging movement of the arm 22 about pivot 19 will carry with it the roller 23 which is thus movable with respect to supporting plate 11.

A pair of fixed rollers 26 and 27 are journalled in plate 11 above lever arm 22 for free running rotation thereon. Rollers 26 and 27 are positioned somewhat forwardly of roller 23 and in the same plane. Roller 26 has a common tangent 28 with roller 23 and roller 27 has -a common tangent 29' with roller 23', such tangents being substantially parallel, as shown.

The end of lever arm 21 is connected to the end of brake pawl arm 16 by means of a spring 30, which is preferably provided with a turnbuckle 31 to adjust the tension thereof. The end of brake pawl arm 15 is connected to a rearwardly extending fixed arm 32 carried by support plate 11 by means of a spring 33 which is also preferably provided with a turnbuckle 34to adjust the tension thereof.

In operation, yarns 3 5 from the spool 9 are trained first over roller 26 in a slightly upwardly inclined di- As previously indicated, tension devices, for carrying out the desirable function describedhave been heretofore providedbut it has been quite difiicult to achieve the posi tive,'unfailing action desired. consistent .with simplicity of construction.

It 'is an object of this tension control. device which is] subject to simple, convenient manufacture, which is effective in achieving constant uniform tension under all conditions of operation,

invention to provide a strand and which is subject to con'venie'ntmaintenance and addevice in accordance standards. Fixed-toeach standard is a bearing bracket 3-having a notch ,4 arranged to receive. the end portion 5 of 'a spindle 6 which is thus rotatably mounted therein for convenient' jr'emoval and replacement as desired. Fixed to one end of thespindle. is a brake'drum 7. The

spindle is adapted to receive the core-8 of a spool of'yarn I 9.- The core and spool are releasably fixed to the spindle by any conventional means in the usual manner whereby the spindle rotateswith thespool'. I

Fixed to standard 1, as by brackets 10,- is a plate 11 extending forwardly of the standard and the spool'rotatably supported thereby. V v v A brake pawl 12 is pivoted at 13 to a bracket 14tixed 'to standard 1 above the plate 1 1. The} pawl 12 has a relatively short arm 15- ext'ending rearwardly of the standard and a relatively long arm 16 extending forwardly of the standard. The pawl12'also has a downwardly projecting brake arm 17 pivotally carrying a. brake shoe 18 engageable with the periphery of brake drum 7;

I Pivoted at 19 to thelower'forward portion of plate 11 I couple will have to be balanced by an equally constant.

is alever member20 in the form of a plate. The lever rection, then rearwardly' and downwardly along tangent 28 to roller 23, then forwardly and upwardly along tangent 29 to roller 27, and then forwardly and downwardly to the loom (not shown) which, it may be assumed, is in operation and is withdrawing the yarns. It will thus .be apparent that a rearwardly extending yarn loop 36 is produced by the rollers26, 23 and 27. In the operational position of the elements, the balancing of the brake pawl 12, lever member 20, by means of springs 30 and 33, and the yarn tension, is such that the brake is applied and the spool 9 therefore is therefore restrained from rotation. Continued withdrawal of yarns by the loom will therefore swing lever arm 22 in a clockwise direction by reason of the pull on roller 23 by the yarns. The yarn loop 36 thus tends to flatten, tangents 28 and 29 remaining always substantially parallel, and such loop provides a supply of yarns for the loom despite the cessation of rotation of the spool. However, as lever arm 22 moves upwardly in clockwise movement, lever arm 21 also moves downwardly in clockwise movement. This movement eventually increases tension on spring 30 to a predetermined value at which the force of spring 33 is overcome and brake pawl 12 swings on its pivot, arms 15 and 17 moving upwardly to disengage the brake shoe 18 from the drum 7. Spool 9 is now free to rotate and the yarns supplied thereby will permit counterclockwise rotation of lever member 20 and its arms 21 and 22. Roller 23 thus moves away from rollers 26 and 27 again to form a loop 36 of increased extent and upward movement of arm 21 releases tension on spring 30 with consequent reapplication of the brake and cessation of rotation of spool 9. The described cycle then begins again and is successively repeated.

7 It will be apparent that the forces imposed on roller 23 by the yarns are imposed practically tangentially to a fixed are having the pivot 19 as its center provided that the extent of such are is maintained within a predetermined and relatively small value. 'This value may be, for example, 30 degrees, as indicated at 37. The resulting couple is, obvious-1y, the product of the tangentially imposed forces and the length of the lever arm relatively to pivot 19, such length remaining at all times, as indicated above, substantially constant. It will further be apparent that if, on .the other side of pivot 19, that is,

on arm 21, a constant couple is provided, such a constant,

couple on arm 22 if equilibrium is to be achieved. Since, however, the lever arm of the couple on arm 22 remains constant (as indicated above), a constant force will, as a result, be applied to roller 23 and, therefore, as a consequence, a constant tension on the yarn.

The structure of the present invention does provide such constant couple or torque on the-forward side of pivot' 19. In effect, during clockwise rotation of the lever member 29, the spring 3!) increases its length and consequently its tension. and the force applied on arm 21. But' the mutual position of the lever arm 2% and the spring 30, and" the relatively short length of arm; 21 are such that, during such clockwise rotation, the lever arm of the increasing force of spring 30 relative to pivot 19 becomes smaller and smaller (see Figure l) in such a proportion as to give a constant couple of said force around pivot 19. Thus, since to a constant couple on one side of pivot 19 must correspond a constant couple on the opposite side, a constant force must be applied to roller 23 and consequently a constant tension on the yarn. Therefore, any'variations in tension of the yarn on each side of the loop 29 will immediately be removed by adjustment of such loop.

It will be apparent that the springs 36 and 33 may be adjusted to actuate the brake within the predetermined angular range of the lever member 20. Thus the yarn will always have a constant tension independently of movements of the spool.

Ifa greater or less tension on the yarn is desired, it is simply necessary to adjust the position of roller 23 on the member 20'.

In order to permit replacement of spool 9, manually operable brake release means are provided. Such means may comprise a handle 38 pivoted to arm 32 at 39 and carrying a bracket 40 having a pin 41 to which is connected the end of spring 33. Pin 41 is eccentrically positioned with respect to pivot 33 whereby swinging movement of the handle will release tension on spring 33 and permit disengagement of the brake.

While the device has been described as applied to a spool for feeding yarns to a loom, it will be understood that it may be applied to any strand tension control.

I claim:

1. A strand tension control device comprising a supporting plate, a lever member pivotally mounted on said plate and having a pair of arms, a roller mounted on one of said arms and swingable therewith, a pair of rollers mounted in adjacent relation about fixed axes on said plate for rotation thereabout, all of said rollers being in substantially coplanar relation, brake pawl having a fixed pivot above said plate, said brake pawl having a brake shoe and a pair of arms extending in opposite directions from said pivot, a spring connecting the free end of one of said'brake pawl arms to said other arm of said lever member, and a spring connecting the free end of the other of said brake pawl arms to said plate.

2. A strand tension control device comprising a supporting plate having a forward portion and a rearward portion, a lever member pivotally mounted on the forward portion of said plate and in generally parallel relation thereto, said lever member having a pair of arms, a roller mounted on one of said arms and swingable therewith, a pair of rollers mounted in adjacent relation about fixed axes for rotation thereabout on the forward portion of said plate forwardly of said first roller, all of said rollers being in substantially coplanar relation, a brake pawl having a fixed pivot above said plate, said brake pawl having a brake shoe and a pair of arms extending opposite directions from said pivot, a spring connecting one of said brake pawl arms to said other arm of said lever member, and a spring connecting the free end of the other of said brake pawl arms to the rearward portion of said plate.

3. A strand tension control device as defined in claim 2, each of said second rollers having a common tangent .with

said first roller, said tangents being substantially parallel.

4. A strand tension control device as defined in-claim 3', said first spring having a position relatively to said other arm of said lever member throughout the swinging movements thereof providing a substantially constant couple of the variable force of said first spring about the axis of said lever member.

5. A strand tension control device comprising a supporting plate, means. for fixedly mounting said plate in upright position, said plate having a forward portion and a rearward portion, a lever member pivotally mounted on the forward portion of said plate and in generally parallel relation thereto; said lever member having an arm overlying said plate and an. arm projecting forwardly thereof, a roller mounted on said overlying arm and swingable therewith, a pair of rollers mounted in adjacent relation about fixed axes for rotation thereabout on the forward portion of said plate above said first roller, all of' said rollers being insubstantially coplanar relation, a. brake pawl, means pivotally mounting said brake pawl about a fixed pivot above said supportingplate, said brake pawl having an arm extending forwardly of said pivot, an arm extending rearwardly of said pivot, a downwardly extending arm, and a brake shoe carried by said downwardly extending arm, a spring connecting the free end of said forwardly extending arm of said brake pawl to said forwardly'projecting arm of said lever member, and a spring connecting the free end ofsaid r'earwardly extending arm of said brake pawl to said rearward portion of said plate.

6; A strand tension control device as defined in claim 5, including separate means for adjusting the tension of each of saidsprings. v

7. A strand tension control device as defined 'in claim 5, including manually ac'tuable means for releasing the tension of said last-mentioned spring.

8. A yarn tension control device comprising a fixed support, a spool carrying means rotatably mounted in said support and having a brake drum, a supporting plate fixed in upright position to said support and having portions extending forwardly and rearwardly of said spool carrying means, a lever member pivotally mounted on the forward portion ofsaid plate and in generally parallel relation thereto, said lever member having an arm overlying said plate and an arm projecting forwardly thereof, a roller mounted on said overlying arm and swingable therewith, a pair of rollers mountediri adjacent relation about fixed axes for rotation thereabout on the forward portion of said plate above said first roller, a brake pawl pivotally mounted on said support'above said supporting plate and having a fixed pivot, an arm extending forwardly of said pivot, an arm extending rearwardly of saidpivot, a downwardly extendingarm, and a brake shoe'carrie'd by said downwardly extending arm and eng'ag'eable' with said" brake drum, a spring connecting the free end of said forwardly extending arm of said brake pawl to said forwardly projecting arm of said lever mem ber, and a spring'conne'ctingthe free end of said rearwardly extending arm of said brake pawl to said rearward portion of said plate.

9. A yarn tension control device comprising a fixed support, spool carrying means rotatably mounted about a fixed axis on said support and having a brake drum, a lever member pivotally mountedon. said support about an. axis parallel to said axis of said spoolcarrying means, said lever member having a first arm projecting rearwardly towards said spoolcarrying means and a second arm projecting forwardly away from said spoolcarrying means, a yarn-receiving roller mounted on said first arm and'having an axis of rotation parallel to said fixed axis, a pair of adjacent yarn-receiving rollers mounted about fixedaxes for rotationth ereabout on said support, a brake pawl having a fixed pivot onsaid support for swinging movement. thereabout, an arm extendingforwardly of said-pivot, an arm extending rearwardly ofsaid'pivot,

and a brake shoe engageable with said brake drum, a

spring connecting the free end of said forwardly extending arm of said brake pawl to said second arm of said lever member, and a spring connecting the free end of said rearwardly extending arm of said brake pawl to said first arm of said lever member, said first spring having a position relatively to said second arm of said lever.

support and having a brake drum, a supporting plate \fixed in upright position to said support and having portions extending forwardly and rearwardly of said-spool carrying means, a lever member pivotally mounted on the forward portion of said plate about a fixed axis and in generally parallel relation thereto, said lever member having an arm overlying said plate and an arm projecting forwardly thereof, a yarn-receiving roller mounted on said overlying arm and having an axis of rotation parallel to said fixed axis, a pair of yarn-receiving rollers mounted in adjacent relation about fixed axes for rotation thereabout on the forward portion of said plate above said first roller, a brake pawl having a fixed pivot on said support for swinging movement thereabout above said supporting plate and having an arm extending forwardly of said fixed pivot, an arm extending rearwardly of said fixed pivot, a downwardly extendingarm, and a brake shoe carried by said downwardly extending arm and engageable with said brake drum, a spring connecting the free end of said forwardly extending arm of said brake pawl to said forwardly projecting arm of said lever member, a spring connecting the free end of saidrearwardly extending arm of said brake pawl to said rearward portion of said plate, and separate means for adjusting the tension of each of said springs.

11. A yarn tension control device as defined in claim 10, the point of connection of said first spring with said forwardly extending arm of said brake pawl being at a distance from said brake pawl axis greater than the distance of the point of connection of said second spring with said rearwardly extending arm of said brake pawl from said brake pawlaxis.

12. A yarn tension control device as defined in claim 10, including means for varying the position of, said first roller axis of rotation with respect to said lever member.

References Citedin the file of this patent FOREIGN PATENTS 

